Prosecutors are questioning former industry minister Paik Un-gyu over allegations that he and others pressured public firm chiefs appointed under the previous administration to step down.

According to legal circles on Thursday, the Seoul Eastern District Prosecutors Office summoned Paik in the morning as a suspect in what has been dubbed the "industry ministry blacklist" case.

He is accused of power abuse by ordering ministry employees in 2017 to pressure the heads of state-run companies to resign.

Last month, investigators searched his residence and his office at Hanyang University and seized materials such as emails from his personal computer.

Paik, who was on site while the raids were taking place, denied there was any connection to the Moon Jae-in administration, saying he did not act on an order and consistently complied with the law and regulations.

The probe, which began in March, may reach the higher-ups of the previous Moon government, according to some observers, but no former presidential official has yet been questioned.

The current People Power Party's predecessor, the Liberty Korea Party, lodged a complaint against Paik and other ministry officials in 2019, accusing them of power abuse.